Rimless spectacles or spectacles where mounting is via bores provided through the thickness of each lens, are in increasingly widespread use.
Reference can be made to Documents WO-2004/003632A, WO-02/21193A, EP-61107042A, WO-96/05535A, U.S. Pat. No. 66,447,117A, WO-00/26716A, EP-1382988A, WO-03/014804A, WO-02/095482A and WO-02/095481A.
In most of the above-cited arrangements, each lens is provided with a through bore and with an outwardly-open side notch, or else with two through bores for respective ones of the component elements of the frame, namely the bridge and the two side arms.
Document U.S. Pat. No. 5,835,183 A provides hinge elements that are fixed to the side portions of the lenses via respective S-shaped portions. The free end of each of the S-shaped portions passes through a through bore, and its central branch passes through an outwardly-open side notch. The end portion thus forms a loop, which is designed to clamp the intermediate portion of the lens resiliently, the clamping being reinforced by elements for increasing friction resistance, in particular by means of teeth biting into the surface of the corresponding lens in the through bore and in the outwardly-open side notch. However, that suffers from the drawback of degrading the surface of the lens that is thus scraped by the teeth, and of weakening that zone of the lens which is clamped between the two clamp-forming portions of arm, which zone is sometimes narrow.
Documents JP2002/318 372 A and EP 0 814 359 A illustrate wire frames having arms that are provided with hinges or else that are not provided with hinges but that are suitable for flexing. Each of those arms presents a distal end that is hook-shaped, and an arm end portion passing into an outwardly-open side notch in the corresponding lens, and a short clamping portion passing through a bore in the lens, these two portions forming a clamp that clamps that portion of the lens which lies between the bore and the outwardly-open side notch in order to hold the arm in place. Clamping of the lens is further reinforced in the arrangement of Document JP 2002/318 372A due to the short portion sloping towards the arm end portion, and due to the axis of the bore through the lens sloping correspondingly, optionally with a plug being interposed in the notch so that, via its flange, it forms a spacer preventing the clamping from loosening.
It has also been proposed to make rimless-type spectacles whose side arms are suitable for flexing without being hinged. For that purpose, a forming technique is used that makes advantageous use of the shape memory capacities of certain metal alloys. For fastening such hinge-less flexing arms, use is generally made of studs that are fitted into bores, as described, for example, in Documents WO-03/083553A and U.S. Pat. No. 5,367,344A.
In most cases, the fastening ends of the side arms present complex configurations, with multiple bends, involving a manufacturing cost that is high. In addition, it is sometimes necessary to form said bends in situ, after threading a rectilinear and not yet bent arm end into a bore through the glass, which is particularly awkward for the operator.